Data streaming for solid-state bulk storage devices

ABSTRACT

Methods facilitate data streaming in bulk storage devices by generating linked lists containing entries for both user data and metadata. These linked lists containing mixed data types facilitate receiving and outputting user data, and to insert or ignore, respectively, metadata corresponding to that user data without interrupting flow of the user data.

RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 12/327,879, titled, “DATA STREAMING FOR SOLID-STATE BULK STORAGEDEVICES,” filed Dec. 4, 2008 (allowed), which is commonly assigned andincorporated herein in its entirety. This application further claimspriority to Chinese Patent Application Serial No. 0810211463.7 filedSep. 26, 2008, entitled “DATA STREAMING FOR SOLID-STATE BULK STORAGEDEVICES,” which is commonly assigned.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor memory, and inparticular, in one or more embodiments, the present disclosure relatesto methods and apparatus providing control of data streaming forsolid-state bulk storage devices.

BACKGROUND

Electronic devices commonly have some type of bulk storage deviceavailable to them. A common example is a hard disk drive (HDD). HDDs arecapable of large amounts of storage at relatively low cost, with currentconsumer HDDs available with over one terabyte of capacity.

HDDs generally store data on rotating magnetic media or platters. Datais typically stored as a pattern of magnetic flux reversals on theplatters. To write data to a typical HDD, the platter is rotated at highspeed while a write head floating above the platter generates a seriesof magnetic pulses to align magnetic particles on the platter torepresent the data. To read data from a typical HDD, resistance changesare induced in a magnetoresistive read head as it floats above theplatter rotated at high speed. In practice, the resulting data signal isan analog signal whose peaks and valleys are the result of the magneticflux reversals of the data pattern. Digital signal processing techniquescalled partial response maximum likelihood (PRML) are then used tosample the analog data signal to determine the likely data patternresponsible for generating the data signal.

HDDs have certain drawbacks due to their mechanical nature. HDDs aresusceptible to damage or excessive read/write errors due to shock,vibration or strong magnetic fields. In addition, they are relativelylarge users of power in portable electronic devices.

Another example of a bulk storage device is a solid state drive (SSD).Instead of storing data on rotating media, SSDs utilize semiconductormemory devices to store their data, but often include an interface andform factor making them appear to their host system as if they are atypical HDD. The memory devices of SSDs are typically non-volatile flashmemory devices.

Flash memory devices have developed into a popular source ofnon-volatile memory for a wide range of electronic applications. Flashmemory devices typically use a one-transistor memory cell that allowsfor high memory densities, high reliability, and low power consumption.Changes in threshold voltage of the cells, through programming of chargestorage nodes (e.g., floating gates or trapping layers) or otherphysical phenomena (e.g., phase change or polarization), determine thedata value of each cell. Common uses for flash memory and othernon-volatile memory include personal computers, personal digitalassistants (PDAs), digital cameras, digital media players, digitalrecorders, games, appliances, vehicles, wireless devices, mobiletelephones, and removable memory modules, and the uses for non-volatilememory continue to expand.

Unlike HDDs, the operation of SSDs is generally not subject tovibration, shock or magnetic field concerns due to their solid statenature. Similarly, without moving parts, SSDs have lower powerrequirements than HDDs. However, SSDs currently have much lower storagecapacities compared to HDDs of the same form factor and a significantlyhigher cost for equivalent storage capacities.

In the efficient movement of data between data storage devices and dataproducer/consumer devices of an electronic system, direct memory access(DMA) has been developed to permit direct access to the storage devicewhile allowing the primary processor of the electronic system to tend toother tasks. In such systems, data is often transferred to or from thestorage devices in packets of defined size. These packets when receivedby a bulk storage device are often stored in volatile storage using alinked-list protocol. This facilitates efficient data transfer withoutwaiting for data to be written to a non-volatile storage area of thebulk storage device.

Flash memory devices generally utilize some non-user data, oftenreferred to as metadata, stored along with the user data. As an example,status indicators, error correction code data, mapping information andthe like, generated by the bulk storage device, might be stored alongwith the user data. Storing these two data types together results instreaming a defined unit of user data to a memory device, and theninterrupting the streaming of user data to fill subsequent write latcheswith the metadata. Once the metadata is written to the memory device,another defined unit of user data may be streamed. This periodicinterruption of user data can lead to inefficiencies as the bulk storagedevice manages the traffic between the different data types to itsnon-volatile storage areas.

For the reasons stated above, and for other reasons which will becomeapparent to those skilled in the art upon reading and understanding thepresent specification, there is a need in the art for alternativecontrol of data streaming for bulk storage devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of an electronic system having atleast one memory module according to an embodiment of the disclosure.

FIG. 2 is a block schematic showing additional detail of a mastercontroller of FIG. 1 in accordance with an embodiment of the disclosure.

FIG. 3 is a representation of one embodiment of a data structure of apage in accordance with an embodiment of the disclosure.

FIG. 4A is an representation of a linked list in accordance with anembodiment of the disclosure.

FIG. 4B is a representation of a portion of the volatile memory showingconceptually how various data units are stored and accessed inaccordance with an embodiment of the disclosure.

FIG. 5 is a flowchart of a method of writing data to a bulk storagedevice in accordance with an embodiment of the disclosure.

FIG. 6 is a flowchart of a method of reading data from a bulk storagedevice in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

In the following detailed description of the present embodiments,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration specific embodiments inwhich the embodiments may be practiced. These embodiments are describedin sufficient detail to enable those skilled in the art to practice theinvention, and it is to be understood that other embodiments may beutilized and that process, electrical or mechanical changes may be madewithout departing from the scope of the present disclosure. Thefollowing detailed description is, therefore, not to be taken in alimiting sense.

FIG. 1 is a block diagram of a solid state drive (SSD) 100, i.e., a bulkstorage device, in communication with (e.g., coupled to) a processor 130as part of an electronic system 120, according to one embodiment of thedisclosure. The electronic system 120 may be considered a host of theSSD 100 in that it controls the operation of the SSD 100 through itsprocessor 130. Some examples of electronic systems include personalcomputers, laptop computers, personal digital assistants (PDAs), digitalcameras, digital media players, digital recorders, electronic games andthe like. The processor 130 may be a disk drive controller or otherexternal processor. Typically there exists a communication bus 132employing a standard protocol that is used to connect the processor 130and the SSD 100. The communication bus 132 typically consists ofmultiple signals including address, data, power and various I/O signals.The type of communication bus 132 will depend on the type of driveinterface being utilized in the system 120. Examples of someconventional disk drive interface bus protocols are IDE, ATA, SATA,PATA, Fibre Channel and SCSI. Other drive interfaces exist and are knownin the art. It should be noted that FIG. 1 has been simplified to focuson the embodiments of the disclosure. Additional or differentcomponents, connections and I/O signals could be implemented as areknown in the art without departing from the scope of the disclosure. Forexample, the SSD 100 could include power conditioning/distributioncircuitry, a dedicated controller for volatile memory 114, etc. However,such additional components are not necessary to an understanding of thisdisclosure.

The SSD 100 according to one embodiment of the disclosure, asillustrated in FIG. 1, includes an interface 102 to allow a processor130, e.g., a drive controller, to interact with the SSD 100 overcommunication bus 132. The interface 102 may be one of many standardizedconnectors commonly known to those skilled in the art. Some examples ofthese interface 102 connectors are IDE, ATA, SATA and PCMCIA connectors.As various embodiments of the disclosure can be configured to emulate avariety of conventional type HDDs, other disk drive connectors may alsobe utilized at the interface 102.

The SSD 100 of FIG. 1 also includes a master controller 104, a number ofmemory modules 106 ₁-106 _(N), and a volatile memory 114. Some of thefunctions performed by the master controller 104 are to manageoperations within the SSD 100 and communicate with devices external tothe SSD 100 such as the processor 130 over the communication bus 132.Memory modules 106 ₁-106 _(N) act as the bulk storage media for the SSD100. Volatile memory 114 acts as buffer storage for data transfers toand from the SSD 100.

The master controller 104 manages the various operations of the SSD 100.As discussed, an SSD may be used as a drop in replacement for a standardHDD and there exist many standardized HDDs which have standardinterfaces and communication protocols. Thus, one of the many functionsof the master controller 104 is to emulate the operation of one of thesestandardized HDD protocols. Another function of the master controller104 is to manage the operation of the memory modules 106 installed inthe SSD 100. The master controller 104 can be configured to communicatewith the memory modules 106 using a variety of standard communicationprotocols. For example, in one embodiment of the disclosure, the mastercontroller 104 interacts with the memory modules 106 using a SATAprotocol. Other embodiments may utilize other communication protocols tocommunicate with the memory modules 106. The master controller 104 mayalso perform additional functions relating to the memory modules such asECC checking Implementation of the master controller 104 may beaccomplished by using hardware or a hardware/software combination. Forexample, the master controller 104 may be implemented in whole or inpart by a state machine. The master controller 104 is further configuredto perform one or more methods of the present disclosure.

Memory modules 106 are coupled to the master controller 104 usinginternal communication bus 112. Communication between the mastercontroller 104 and the memory modules 106 may be implemented byutilizing a common bus 112 as shown, and/or discrete connections betweenthe master controller 104 and each memory module 106.

Control circuitry 110 manages the operation of the non-volatile memorydevices 116 on its corresponding memory module 106 ₁-106 _(N). Memorydevices 116 may be flash memory devices. The control circuitry 110 mayalso act to translate the communication protocol utilized by the mastercontroller 104 to communicate with the memory module 106 ₁-106 _(N). Forexample, in one embodiment of the disclosure, the master controller 104may be utilizing an SATA protocol to interact with the memory modules106 ₁-106 _(N). In such an embodiment, the control circuitry 110 isconfigured to emulate a SATA interface. The control circuitry 110 canalso manage other memory functions such as security features to regulateaccess to data stored in the memory module and wear leveling.

As noted above, the insertion of data generated at a bulk storage deviceinto streams of user data received from an external device can lead toinefficiencies as the streaming is interrupted while the insertion iscarried out at the bulk storage device. Various embodiments address thisissue by generating a linked list that contains entries for the two datatypes. The entries have a defined order. For example, the linked listmight be defined to have three entries for user data followed by oneentry for metadata. This facilitates streaming data having a defineddata structure.

Linked-list protocols provide for efficient streaming of data bydefining a size of a unit of data to transfer and a starting address forthat unit of data. In this manner, data can be streamed beginning at astarting address and continuing through subsequent consecutive addressesuntil the defined size has been transferred. The next entry in thelinked list then defines the size of the next unit of data and itsstarting address, and the process can be repeated.

In prior systems, as user data was received by a bulk storage device, itwould be stored to volatile memory. A linked list would be generateddefining the size of data units to be stored in the volatile memory andthe starting addresses of where each of those data units would bestored. As the master controller would subsequently stream those dataunits to its non-volatile memory modules, it would poll for a number ofunits transferred and then interrupt data transfer to the memory moduleto begin transferring metadata after a particular number of units ofuser data had been transferred. After transferring the metadata wascomplete, the master controller would then refer back to the linked listto re-initiate streaming of user data according to the next entry of thelinked list.

Various embodiments described herein insert linked list entries formetadata within the user data entries. A value is defined for the numberof user data entries to be created before a metadata entry is inserted.For example, user data may be received by the SDD 100 in units of aparticular size, such as one sector. Thus, each linked list entry foruser data would define a size indicative of the received unit of userdata and the starting address as selected by the master controller 104for storage of that received unit in the volatile memory 114. Note thata sector is often taken to be 512 Bytes, although there is norequirement to define the data units by sector, or to use 512 Bytes as asector size. To continue with this example, if it is desired to writeuser data to a memory device configured for 4 KB of user data and 80Bytes of metadata per page, and to separate the page into two sectionsof user data of 2 KB each, with each section of user data followed by asection of metadata of 40 Bytes each, the value in this example would beselected to be four, such that four linked list entries would be createdfor the received user data, each having a defined size of 512 Bytes,followed by a linked list entry for the metadata defining a size of 40Bytes.

The receipt of user data does not need to be interrupted for theinsertion of the metadata entry, and the metadata corresponding to thatentry does not have to be generated prior to creation of the linked listentry. Because the master controller 104 knows the size of thecorresponding metadata unit, it merely reserves the storage areas in itsvolatile memory 114 defined by the metadata unit size and the startingaddress. As some metadata may require calculations based on the receiveduser data, e.g., the generation of error correction code (ECC) data, itwould interrupt data flow to require calculation of that data before thenext user data could be received. By simply reserving a storage locationfor the data, and creating its linked-list entry as described, once themetadata is generated and stored, the user data and its correspondingmetadata may be streamed to a memory module 106 without interruption,thus permitting the master controller 104 to utilize its processingresources for other tasks, such as wear leveling and signal processing.

While the foregoing example described an embodiment for receipt of userdata for writing to a memory module, the concepts described herein arealso applicable to reading user data from a memory module. Thus, thelinked list would be created defining the size and locations of userdata units and metadata units to be received from the memory modules.Data would then be streamed from a memory module and stored to theaddresses as defined in the linked list. The user data would then beavailable for output on the communication bus 132.

FIG. 2 is a block schematic showing additional detail of the mastercontroller 104 of FIG. 1 in accordance with an embodiment of thedisclosure. In FIG. 2, the master controller 104 includes a processor218. The processor 218 provides for general operations of the SSD 100.For example, the processor 218 may perform signal processing to evaluatethe signals received from the memory modules 106 and wear leveling tomaintain relatively even usage of the various memory devices. Theprocessor 218 may further decode commands received from an externaldevice. For one embodiment, the processor 218 generates the linked listsas described herein.

The master controller 104 may further include a volatile memorycontroller 222 and a non-volatile memory controller 224 for control andaccess of the volatile memory 114 and non-volatile memory modules 106,respectively. In various embodiments, processor 218 may be configured togenerate the linked lists, while the non-volatile memory controller 224may be configured to stream data as defined by the linked lists to andfrom the memory modules 106 without further trafficking by the processor218.

FIG. 3 is a representation of one embodiment of a data structure of apage 330 in accordance with an embodiment of the disclosure. The page330 has one or more user data portions 332 and one or more metadataportions 334. Metadata portions 334 contain data that is generally notreceived from an external device for storage on a memory device forsubsequent retrieval by an external device. Examples include a logicaladdress of the page 330, ECC data, status indicators, etc. As oneexample, each user data portion 332 contains 2,048 Bytes of user dataand each metadata portion 334 contains 48 Bytes of metadata. A page 330may further include additional data portions (not shown) for otherpurposes a designer might choose.

Because the external device providing user data to the SSD 100 during awrite operation is generally not aware of the metadata, it wouldtypically provide the user data to be programmed to a logical address,e.g., the address corresponding to the page 330, in one stream of data.As noted above, this stream of user data may contain one or more unitsof defined size, e.g., units of a sector of data. For variousembodiments, in response to receiving a command to write user data to alogical address, the master controller 104 generates a linked list todefine unit sizes and locations for storage of the user data. The mastercontroller 104 further generates entries in the linked list to defineunit sizes and locations for storage of metadata. The structure of thelinked list would follow the desired data structure of the page 330. Forexample, where user data portions 332 a and 332 b are 2,048 Bytes each,metadata portions 334 a and 334 b are 48 Bytes each, user data units are512 Bytes each and metadata units are 48 Bytes each, the linked list fora read or write of page 330 would contain four (2,048 Bytes/512 Bytes)user data entries, followed by one metadata entry, followed by four userdata entries, followed by one metadata entry. Each user data entry woulddefine a size of 512 Bytes and each metadata entry would define a sizeof 48 Bytes.

FIG. 4A is a representation of a linked list 440 in accordance with anembodiment of the disclosure. Linked list 440 includes one or more userdata entries 442 and one or more metadata entries 444. The dashed linein each of the user data entries 442 and metadata entries 444 indicatesthat each entry defines both a size of the data unit for that entry anda starting address for that data unit.

FIG. 4B is a representation of a portion of the volatile memory 114showing conceptually how the various data units are stored and accessedfor transfer to a memory module. The volatile memory 114 has one or moresub-segments 446. Each sub-segment 446 represents contiguous addressspace within the volatile memory 114, although the individualsub-segments 446 need not have the same size. As user data units, e.g.,user data 0-7 in FIG. 4B, are received by the SSD 100, each user dataunit is stored in a sub-segment 446 as defined by the linked list 440.Note that although sub-segments 446 represent contiguous address space,individual user data units need not be stored to contiguous sub-segments446. For example, there may be storage locations between where user data2 ends and user data 3 begins. These storage locations may be unused, orthey may already be designated for storage of other data used byprocessor 218.

Metadata units, e.g., metadata 0-1 in FIG. 4B, may be written tovolatile memory 114 while user data units are being received or afterthat data transfer is complete. Metadata units are stored in asub-segment 446 as defined by the linked list 440. As with user data,individual metadata units need not be stored to contiguous sub-segments446. However the data of the metadata units is stored in consecutiveaddress spaces of the individual sub-segments 446.

Entries for the linked list 440 are programmed prior to receiving datacorresponding to those entries. However, the entire linked list 440 neednot be created prior to completing a data transfer. For example, where ahost device issues a write command to the SSD 100, the write command maybe followed by 8 user data units. Thus, while a linked-list entry iscreated for a first user data unit before receiving the first user dataunit, subsequent linked-list entries may be created while the first userdata unit is being received. Also, linked-list entries for the metadataunits are created before writing the metadata to the volatile memory 114for subsequent streaming, but need not be created prior to generatingthe metadata.

Various embodiments may further control when metadata units aretransferred to the volatile memory 114, or when they are transferred tothe memory modules 106. For example, metadata should not be transferredto the volatile memory 114 until its corresponding linked-list entriesare programmed with valid starting addresses. In addition, because somemetadata may not be generated until after transfer of the user data iscomplete, streaming of such metadata to a memory module 106 should bedelayed until after the sub-segment defined by the linked list containsvalid metadata. Thus, the non-volatile memory controller 224 may beconfigured to prohibit storage of metadata to the volatile memory 114streaming of metadata until its corresponding linked-list entry 444 hasbe generated, and to prohibit streaming of metadata from the volatilememory 114 until after the sub-segment 446 defined by the linked listcontains valid metadata.

For transfer of user data units and metadata units to a memory modulefor non-volatile storage of the data, the non-volatile memory controller224 then streams the data from the volatile memory according to thelinked list 440. Thus, as depicted in FIG. 4B, user data 0 is providedto the memory module, followed by user data 1-3. Upon completion of thetransfer of user data 3, metadata 0 is transferred, followed by userdata 4-7, and then metadata 1. In this manner, user data and metadataare provided to the memory module having the defined data structure andwithout requiring interruption of the data streaming operation by theprocessor 218 for insertion of metadata. Because metadata is generallynot provided to an external device, when responding to a read command ofthe SSD 100, data streaming from the volatile memory 114 to thecommunication bus 132 should skip the metadata entry 444 in the linkedlist 440.

FIG. 5 is a flowchart of a method of writing data to a bulk storagedevice in accordance with an embodiment of the disclosure. At 550, awrite command is decoded. The decoding may generally be performed by theprocessor of the master controller of the bulk storage device.

A write command is an externally-provided command that defines at leasta logical address to where user data is to be written. The write commandfurther provides the user data to be written to the bulk storage device.While the write command may define a user data unit size, this may bedefined by protocol. Thus, a write command of a given protocol maydefine a number of user data units to follow the command and a size ofeach of the units without a need to explicitly provide that with thecommand.

At 552, in response to decoding the write command, the linked list isgenerated. The linked list will have a defined number of entries foruser data, a defined number of entries for metadata, and a defined orderof the entries. As noted above, each linked-list entry will define aunit size of the data to be stored and a starting address to where thatunit of data is to be stored. The linked-list entries do not need todefine what type of data is stored at their corresponding addresses. Forexample, the processor of the master controller of the bulk storagedevice can be configured such that it generates linked lists to storeuser data units at the addresses of a particular number of the entriesbefore storing a metadata unit at the address of the next entry. Thelinked list should contain sufficient entries, i.e., a combination of anumber of entries and a size for each entry, such that all user dataassociated with the write command has defined storage locations. Thelinked list will also contain at least one entry for metadata.

At 554, user data received in response to the write command is storedaccording to the addresses and unit sizes defined by the linked-listentries for user data. For example, a host might begin transferring userdata units to the bulk storage device. As a first user data unit isreceived, data of the first user data unit is written to volatile memorybeginning at a location defined by the starting address, and data of thefirst user data unit is then written to subsequent addresses of acontiguous memory space until the size defined by the linked-list entryis reached. The next user data unit received will then be stored tovolatile memory according to the next linked-list entry for user dataand so on until all of the user data associated with the write commandhas been received.

At 556, metadata generated by the bulk storage device associated withthe received user data is stored according to the addresses and unitsizes defined by the linked-list entries for metadata. Although depictedin FIG. 5 to follow the receipt of the user data, some or all of themetadata may be stored according to its linked-list entries before allof the user data has been received. For example, the write command maybe associated with eight user data units. For this example, the bulkstorage device may receive the first four user data units, generatemetadata for those user data units, and store that metadata to volatilememory before the last four user data units are received.

At 558, user data and metadata is streamed to non-volatile memory havinga data structure defined by the linked list. For example, if the linkedlist has four user data entries of 512 Bytes each, one metadata entry of48 Bytes, four user data entries of 512 Bytes each and one metadataentry of 48 Bytes, the structure of the data provided to thenon-volatile memory would have 2,048 Bytes of user data, followed by 48Bytes of metadata, followed by 2,048 Bytes of user data and followed by48 Bytes of metadata.

FIG. 6 is a flowchart of a method of reading data from a bulk storagedevice in accordance with an embodiment of the disclosure. At 660, aread command is decoded. The decoding may generally be performed by theprocessor of the master controller of the bulk storage device.

A read command is an externally-provided command that defines at least alogical address from where user data is to be retrieved. While the readcommand may define a user data unit size, this may be defined by thedata structure of the memory device containing the data. Thus, a datastructure of the memory device may define a number of user data units toretrieve and a size of each of the units without a need to explicitlyprovide that with the command.

At 662, in response to decoding the read command, the linked list isgenerated. The linked list will have a defined number of entries foruser data, a defined number of entries for metadata, and a defined orderof the entries. As noted above, each linked-list entry will define aunit size of the data to be stored and a starting address to where thatunit of data is to be stored, whether that data is received from anexternal device or received from a memory module of the bulk storagedevice. The linked-list entries do not need to define what type of datais stored at their corresponding addresses. For example, the processorof the master controller of the bulk storage device can be configuredsuch that it generates linked lists to store user data units at theaddresses of a particular number of the entries before storing ametadata unit at the address of the next entry. The linked list shouldcontain sufficient entries, i.e., a combination of a number of entriesand a size for each entry, such that all data associated with the readcommand has defined storage locations. The linked list will also containat least one entry for metadata.

At 664, data is read from a memory device of the bulk storage device inresponse to the read command and is streamed to volatile memoryaccording to the addresses and unit sizes defined by the linked-listentries for that data. For example, a read command may result in a pageof data being read from a memory device. This page of data is thenwritten to volatile memory according to the linked-list entries. Forexample, if the linked list has four user data entries of 512 Byteseach, one metadata entry of 48 Bytes, four user data entries of 512Bytes each and one metadata entry of 48 Bytes, the first 2,048 Bytes ofdata is stored according to the first four user data entries, the next48 Bytes of data is stored according to the first metadata entry, thenext 2,048 Bytes of data is stored according to the last four user dataentries, and the next 48 Bytes of data is stored according to the lastmetadata entry. For one embodiment, the non-volatile memory controlleris configured to stream data from a non-volatile memory device to thevolatile memory controller without intervention by the processor of themaster controller. In this manner, while data is being populated to thevolatile memory according to the linked list, the processor is free tohandle other tasks and does not need to be involved in the data transferto volatile memory.

At 666, user data is output to an external device. Metadata is generallyused internally by the bulk storage device and is not meant for use byexternal devices. Accordingly, the linked list can be used to transferonly the user data portions of the retrieved data by simply skipping thelinked-list entries for metadata.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement that is calculated to achieve the same purpose maybe substituted for the specific embodiments shown. Many adaptations ofthe disclosure will be apparent to those of ordinary skill in the art.Accordingly, this application is intended to cover any adaptations orvariations of the disclosure.

What is claimed is:
 1. A method of operating a storage device, comprising: generating a linked list in response to decoding an access command received at the storage device, wherein the linked list has two or more first entries corresponding to user data, two or more second entries corresponding to metadata, and a defined order of the first entries and the second entries corresponding to a defined data structure of a page of data of a first memory of the storage device, wherein each first entry of the linked list identifies a size of a respective portion of user data and a starting address for storage of that portion of user data to a second memory of the storage device, and wherein each second entry of the linked list identifies a size of a respective portion of metadata and a starting address for storage of that portion of metadata to the second memory of the storage device; storing portions of user data and portions of metadata to the second memory according to the sizes and the starting addresses identified by the ordered entries of the linked list; and outputting at least the stored portions of user data from the second memory.
 2. The method of claim 1, further comprising receiving the portions of user data from an external device and generating the portions of metadata by the storage device when the access command is a write command.
 3. The method of claim 2, further comprising generating at least one of the portions of metadata prior to receiving all of the portions of user data.
 4. The method of claim 3, further comprising generating at least one of the portions of metadata after receiving at least one of the portions of user data.
 5. The method of claim 2, wherein generating the portions of metadata further comprises generating at least some metadata in response at least one of the portions of user data.
 6. The method of claim 5, wherein generating at least some metadata in response at least one of the portions of user data comprises generating at least error correction code data for the at least one of the portions of user data.
 7. The method of claim 6, wherein generating at least some metadata further comprises generating metadata comprising status indicators and/or mapping information.
 8. The method of claim 1, further comprising reading user data and metadata from the page of data of the first memory prior to storing the portions of user data and the portions of metadata to the second memory.
 9. The method of claim 1, wherein storing portions of user data and portions of metadata to the second memory comprises storing the portions of user data and the portions of metadata to non-contiguous sub-segments of the second memory.
 10. The method of claim 1, wherein generating a linked list further comprises generating the linked list such that sizes identified for each first entry of the linked list are the same size and sizes identified for each second entry of the linked list are the same size.
 11. The method of claim 10, wherein generating a linked list further comprises generating the linked list such that sizes identified for each first entry of the linked list are different than sizes identified for each second entry of the linked list.
 12. The method of claim 1, wherein generating a linked list further comprises generating the linked list such that sizes identified for each entry of the linked list are defined by sizes of respective portions of data of the defined data structure of the page of data.
 13. The method of claim 1, wherein generating a linked list further comprises generating the linked list such that the defined order of the first entries and the second entries comprises interleaving instances of the second entries with instances of the first entries.
 14. The method of claim 1, wherein generating a linked list having a defined order of the first entries and the second entries corresponding to a defined data structure of a page of data of a first memory of the storage device comprises generating the linked list such that the order of the first entries and the second entries of the linked list matches an order of portions of user data and portions of metadata as would be stored to the page of data of the first memory.
 15. The method of claim 1, further comprising: when the access command is a read command: storing portions of user data and portions of metadata to the second memory according to the sizes and the starting addresses identified by the ordered entries of the linked list comprises streaming data from the first memory to the second memory according to the sizes and the starting addresses identified by the ordered entries of the linked list; and outputting at least the stored portions of user data from the second memory comprises outputting only the stored portions of user data from the second memory to an external device; and when the access command is a write command: storing portions of user data and portions of metadata to the second memory according to the sizes and starting addresses identified by the ordered entries of the linked list comprises storing portions of user data received from the external device and portions of metadata generated by the storage device to the second memory according to the sizes and starting addresses identified by the ordered entries of the linked list; and outputting at least the stored portions of user data from the second memory comprises streaming the stored portions of user data and the stored portions of metadata from the second memory to the first memory in the defined order of the respective entries of the linked list such that the streamed data satisfies the defined data structure of the page of data of the first memory.
 16. A method of operating a storage device, comprising: generating a linked list in response to decoding a write command received at the storage device from an external device, wherein the linked list has two or more first entries corresponding to user data, two or more second entries corresponding to metadata, and a defined order of the first entries and the second entries corresponding to a defined data structure of a page of data of a first memory of the storage device, wherein each first entry of the linked list identifies a size of a respective portion of user data and a starting address for storage of that portion of user data to a second memory of the storage device, and wherein each second entry of the linked list identifies a size of a respective portion of metadata and a starting address for storage of that portion of metadata to the second memory of the storage device; receiving user data from the external device associated with the write command; storing portions of the user data received from the external device and portions of metadata generated by the storage device to the second memory according to the sizes and starting addresses identified by the ordered entries of the linked list; and streaming the stored portions of user data and the stored portions of metadata from the second memory to the page of data of the first memory as identified by the write command in the defined order of the respective entries of the linked list such that the streamed data satisfies the defined data structure of the page of data of the first memory.
 17. The method of claim 16, further comprising generating at least one of the portions of metadata after receiving at least one of the portions of user data.
 18. The method of claim 17, further comprising generating at least one of the portions of metadata prior to receiving all of the portions of user data.
 19. The method of claim 17, wherein generating at least one of the portions of metadata after receiving at least one of the portions of user data further comprises generating at least some metadata in response at least one of the received portions of user data.
 20. A method of operating a storage device, comprising: generating a linked list in response to decoding a read command received at the storage device from an external device, wherein the linked list has two or more first entries corresponding to user data, two or more second entries corresponding to metadata, and a defined order of the first entries and the second entries corresponding to a defined data structure of a page of data of a first memory of the storage device, wherein each first entry of the linked list identifies a size of a respective portion of user data and a starting address for storage of that portion of user data to a second memory of the storage device, and wherein each second entry of the linked list identifies a size of a respective portion of metadata and a starting address for storage of that portion of metadata to the second memory of the storage device; reading user data and metadata from the page of data of the first memory device as identified by the read command; streaming portions of the user data and portions of the metadata from the first memory to the second memory according to the sizes and the starting addresses identified by the ordered entries of the linked list; and outputting only the stored portions of user data from the second memory to the external device in response to the read command. 